1. Field of the Invention
The present invention relates to the field of band tightening and cutting devices, and in particular, to a device for easily and safely winding and tightening a band around a number of electric wires, and cutting and removing an excess portion of the band.
2. Description of Related Art
A band is often used for bundling a number of electric wires. The electric wires may be used for connection between various kinds of electrical equipment mounted in a vehicle, such as an automobile, or in various kinds of electrical machinery and apparatuses, such as facsimile and copy machines. Generally, such a band includes a band portion that extends from a band base portion having a hooking hole. A band for bundling a number of electric wires may also be called a cable tie. Bundling electric wires with a band is accomplished by encircling the electric wires with the band portion, inserting an end of the band portion into the hooking hole and tightening the band around the electric wires, and cutting and removing an excess portion of the band.
FIG. 8 shows a conventional device and method for bundling a number of electric wires for a wire harness of an automobile. A group of electric wires D constituting a wire harness W/H wired on an assembly board Z is bundled with a band B. While various types of bands are known, a band having hooking blades B-3 at a band base portion B-1 with a band portion B-2 extending therefrom, and that may be installed on an automobile body panel, is shown in the conventional example.
A known device for banding a number of electric wires includes a plurality of wiring jigs 2 having U-shaped receiving portions for supporting electric wires, and a plurality of banding jigs 3 for applying bands to the electric wires, projecting from an assembly board Z. Each banding jig 3 includes a retaining board 3b on the upper end of a support bar 3a that projects from the assembly board Z, and a recessed portion 3c notched into one end of the retaining board 3b. 
To secure a band around a bundle of electric wires, a tube C for protection is wound around the bundle to form a sheath on the outside of the electric wires D wired on the assembly board Z. A worker encircles the band portion B-2 of the band B around a portion of the bundle on which the tube is sheathed and inserts the band portion B-2 into the hooking hole of the band base portion B-1, then inserts the band B in the recessed portion 3c of the banding jig 3. Then, the band portion B-2 is tightened by pulling it while clamping the end of the band portion B-2 with pliers P, then an excess portion of the band portion B-2 that is unnecessary is cut with a nipper N.
As described above, the tightening of the band portion B-2 is performed by a worker who holds the pliers P by grasping, and the tightness of the band portion B-2 depends on the particular workers. Accordingly, the tightness of the band portion B-2 may differ by every worker, and it becomes difficult to maintain a consistent level of product quality. Occasionally, the tube C may be destroyed by over-tightening the band portion B-2. Further, if the pliers P happen to be pulled off the band portion B-2 during tightening, the surroundings may be damaged by the pliers P, and there is a fear that the workers themselves may be injured.
Additionally, considering the above-mentioned banding method from the standpoint of work efficiency, the worker is required to use the pliers P for pulling the band portion B-2, and to use the nipper N for cutting. Therefore, the exchange of holding the nipper N in place of the pliers P is required, the work cannot be continuously performed, and the method is troublesome.
In order to solve the above problems in the prior art, the present invention includes a tightening and cutting device for fastening and cutting a band that bundles a group of electric wires forming a wire harness.
The present invention is directed to a band tightening and cutting device. An object of the invention is to provide a band tightening and cutting device that provides a consistent amount of band tightening, even if the band tightening is performed by different workers. Another object of the invention is to provide a band tightening and cutting device that maintains a consistent level of product quality. Another object of the invention is to provide a band tightening and cutting device that does not require the worker to exchange the holding of tightening and cutting tools. Another object of the invention is to provide a band tightening and cutting device that provides improved operation efficiency. Further, another object of the invention is to provide a band tightening and cutting device for assembling a wire harness for an automobile.
According to an aspect of the present invention, a tightening and cutting device is provided for fastening and cutting a band that bundles a group of electric wires forming a wire harness including a base member having a band-retaining portion on the upper end of a support bar that projects from an assembly board provided at a location on the assembly board corresponding to a bundling location on the assembly board where a band is fastened around a group of electric wires wired on the assembly board. The base member has a band holding member, a band pulling mechanism that may be rotated in a direction so that the band holding member is moved upward, and a cutting blade that is movable to a band retaining portion side of the base member in response to the rotation of the band pulling mechanism. Furthermore, a band base portion of the band is retained by the band-retaining portion and the end of the band portion encircling the electric wires is held by the band holding member, and the band is fastened around the electric wires at a certain location by fastening the band portion and cutting an excess portion of the band.
Thus, when the tightening and cutting device for fastening and cutting a band of the present invention is provided extending from an assembly board, the device of the present invention can be used as a band fastening jig so that the band is positioned against a group of electric wires forming the wire harness and secured around the electric wires. Further, since all of the bundling, tightening and cutting steps can be performed with the device of the present invention, the exchange of holding tools is unnecessary, and the banding operation can be more efficient.
According to a further aspect of the present invention, the band-retaining portion is formed by notching an end part of the base member.
In another aspect of the present invention, the band pulling mechanism includes a substantially L-shaped member having a vertical member and a horizontal member provided on the upper face of the base member, and a rotational member mounted on said vertical member in a freely rotatable manner.
According to a further aspect of the present invention, the device includes a sliding member provided on the horizontal member of the substantially L-shaped member movable in an upward and a downward direction, wherein the sliding member includes a pressure member, and the band holding member and the pressure member are provided on the rotational member.
According to a further aspect of the present invention, the cutting blade may have a cam part on an upper side and may be housed and slidable in a recessed portion in the base member so as to be linked with the band-retaining portion, in a manner in which the cutting blade can slide, and the band portion is pulled by the rotation of the rotational member, the sliding member is moved in a downward direction by the pressure member in response to rotation of the rotational member and contacts the cam part of the cutting blade, and the cutting blade is moved to the band-retaining portion side of the base member to cut an excess portion of the band.
In a further aspect of the invention, the rotational member is rotated, the cutting blade is moved to the band-retaining portion side of the base member by the pressure member by the sliding member, and the band portion may be cut. Therefore, a worker can simultaneously tighten, fasten and cut the band by only rotating the rotational member, the burden on the worker is reduced, and the bundling operation can be easily performed.
According to another aspect of the present invention, the substantially L-shaped member is rotatably mounted on the base member and biased by a spring in a direction in which the band-retaining portion is closed, and the substantially L-shaped member may be rotated against the biased direction to an open position to insert the band base portion of the band in the band-retaining portion. Thus, the insertion and retention of the band base portion may be performed smoothly. Further, during fastening of the band portion, the substantially L-shaped member is biased by the spring to a closed position, the band portion may be pulled in an upward direction, and the band portion may be tightened and fastened.
In a further aspect of the present invention, a lever extends from the rotational member and an adjustable stopper is provided on the rotational member, and the lever contacts the adjustable stopper during the rotation of the rotational member to control the amount of rotation of the rotational member. Thus, when the lever extends from the rotational member, a worker may grasp the lever and rotate the rotational member with little effort. Further, the adjustable stopper that is contacted by the rotated lever is provided on the substantially L-shaped member so that the amount the rotational member rotates can be controlled. Therefore, the amount the rotational member rotates and the tightness of the band portion can be predetermined and do not depend on the particular operator of the device, and the product quality control can be improved. Further, any overtightening of the band and resulting collapse of the protective material around the bundle of wires due to overtightening of the band can be avoided.
According to a further aspect of the invention, a detection probe may be provided in the notched portion of the block for detecting insertion of a band base portion into the band-retaining portion. The detection probe recognizes the presence or absence of the band base portion during operation, and the problem of forgetfulness of the operators can by avoided.
In a further aspect of the present invention, the band-retaining portion includes a pair of generally triangular shaped protrusions extending from a lower face of the base member, a notched portion on an end of the base member between said pair of generally triangular shaped protrusions, and a block provided on the lower face of the base member. The block includes a pair of generally triangular shaped protrusions and a notched portion therebetween, the notched portion being coextensive with said notched portion of said base member, and the pair of generally triangular shaped protrusions on the block are spaced from the pair of generally triangular shaped protrusions on the base member so that blade parts of a band are receivable in the space and a band base portion of a band is receivable in the notched portions to hold the band for tightening and cutting.
According to a further aspect of the present invention, the band holding member includes a fixed holding member provided on the rotational member and including a pressure face, a rotational holding member rotatably mounted on the fixed holding member and including a pressure face, a spring having one end fixed to the rotational member and another end fixed to the rotational holding member, so that the spring biases the pressure faces together to hold a band portion therebetween.
In a still further aspect of the present invention, the L-shaped member includes a recessed portion provided on the vertical member and a recessed portion provided on the horizontal member adjacent the notched portions. A U-shaped shaped guide member is provided on the vertical member in the recessed portion of the vertical member and the recessed portion of the horizontal member, the U-shaped guide member having an insertion guide portion that guides the band portion during the band tightening operation.
According to a further aspect of the present invention, a method is provided for fastening and cutting a band that bundles a group of electric wires forming a wire harness. The method includes providing a band tightening and cutting device, providing a band having a band portion and a band base portion, and inserting the band base portion in a band retaining portion of the band tightening and cutting device. The method further includes encircling a group of wires with the band and inserting an end of the band portion into the band base portion, holding the band portion with a holding member of the band tightening and cutting device, and rotating the holding member and the band portion held thereby so that the band portion is pulled away from the band base portion and the band is tightened around the wires.
In a further aspect of the present invention, the method includes moving a cutting blade on the band tightening and cutting device in response to the rotating and thereby cutting an excess portion of the band, so that fastening and cutting of the band take place in a single operation.